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‘Tear-gas’: authorised at home, banned in war? Not so for the USA

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‘Tear-gas’ may come to symbolise the Trump Administration’s heavy-handed response to the popular reaction against the killing of George Floyd, a middle-aged black man, by a white police officer. The President’s rolling thunder of insensitive, divisive tweets extolling law and order and deriding the legitimate demands by the Black Lives Matter movement has contributed to irresponsible use of force against essentially peaceful protesters, onlookers, and members of the press. Police brutality combined with widespread lack of accountability – unless a person gets killed or an incident is captured on media – has led to multiple types of excesses. When President Trump sallied out of the fenced White House for a photo session in front of the nearby St John’s Episcopal Church, police and National Guard units cleared his path by tear-gassing protesters. Moments earlier he had threatened state governors with the deployment of the US military unless they use the National Guard in sufficient numbers to ‘dominate the streets’.

Over the past weeks many commentators have zoomed in on riot control agents (RCAs), arguing that lachrymators have been internationally banned for war but not for quenching public disturbances or riots. Fact-checker sections in newspapers generally confirm the assertion citing relevant provisions in the Chemical Weapons Convention (CWC). Prominent politicians, city councils, civil rights leaders and many other human rights advocates in the United States are now calling to prohibit RCAs for crowd control purposes.

Anti-Tear-Gas Demonstration, Washington, DC, January 2017 (Picture by Justin Norman)

While valid for the international community, is the assertion that RCAs cannot be used in war correct for the United States?

US ratification of the CWC with reservations

The United States ratified the CWC on 24 April 1997, five days before it was due to enter into force. The Senate’s consent was not a given as certain Republicans, then already convinced that the United States should be able to act with the fewest possible international legal constraints and the broadest impunity, forced the Clinton Administration into accepting significant concessions.

One concession concerns RCAs and amounts to a reservation to the CWC. Section 2 (26) of Senate Resolution 75, 105th Congress, 1st Session (April 24, 1997) identifies ‘permitted uses’ of RCAs not explicitly recognised in the CWC in situations of international armed conflict:

(26) Riot control agents:
     (A) Permitted uses. — Prior to the deposit of the United States instrument of ratification, the President shall certify to Congress that the United States is not restricted by the Convention in its use of riot control agents, including the use against combatants who are parties to a conflict, in any of the following cases:
          (i) United States not a party. — The conduct of peacetime military operations within an area of ongoing armed conflict when the United States is not a party to the conflict (such as recent use of the United States Armed Forces in Somalia, Bosnia, and Rwanda).
          (ii) Consensual peacekeeping. — Consensual peacekeeping operations when the use of force is authorized by the receiving state, including operations pursuant to Chapter VI of the United Nations Charter.
          (iii) Chapter vii peacekeeping. — Peacekeeping operations when force is authorized by the Security Council under Chapter VII of the United Nations Charter.
     (B) Implementation. — The President shall take no measure, and prescribe no rule or regulation, which would alter or eliminate Executive Order 11850 of April 8, 1975.
     (C) Definition. — In this paragraph, the term `riot control agent' has the meaning given the term in Article II(7) of the Convention.

Executive Order 11850, signed by President Gerald Ford on 8 April 1975, provides for the US renunciation of the first use of herbicides and RCAs in war. However, the document also includes four exceptions regarding RCAs:

The United States renounces, as a matter of national policy, first use of herbicides in war except use, under regulations applicable to their domestic use, for control of vegetation within U.S. bases and installations or around their immediate defensive perimeters, and first use of riot control agents in war except in defensive military modes to save lives such as:
     (a) Use of riot control agents in riot control situations in areas under direct and distinct U.S. military control, to include controlling rioting prisoners of war.
     (b) Use of riot control agents in situations in which civilians are used to mask or screen attacks and civilian casualties can be reduced or avoided.
     (c) Use of riot control agents in rescue missions in remotely isolated areas, of downed aircrews and passengers, and escaping prisoners.
     (d) Use of riot control agents in rear echelon areas outside the zone of immediate combat to protect convoys from civil disturbances, terrorists and paramilitary organizations.

I have determined that the provisions and procedures prescribed by this Order are necessary to ensure proper implementation and observance of such national policy.

NOW, THEREFORE, by virtue of the authority vested in me as President of the United States of America by the Constitution and laws of the United States and as Commander-in-Chief of the Armed Forces of the United States, it is hereby ordered as follows:
     Section 1. The Secretary of Defense shall take all necessary measures to ensure that the use by the Armed Forces of the United States of any riot control agents and chemical herbicides in war is prohibited unless such use has Presidential approval, in advance.
     Sec. 2. The Secretary of Defense shall prescribe the rules and regulations he deems necessary to ensure that the national policy herein announced shall be observed by the Armed Forces of the United States.

President Ford issued the Executive Order in conjunction with the US ratification of the 1925 Geneva Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare on 10 April 1975.

It should be emphasised that the reservation to the CWC precludes any change to the policy: ‘The President shall take no measure, and prescribe no rule or regulation, which would alter or eliminate Executive Order 11850 of April 8, 1975’. Furthermore, the list with circumstances in which RCAs may be used is not limitative.

US military doctrine

Now, the CWC is not exactly clear about the meaning of ‘law enforcement’ and ‘domestic riot control’, which has allowed the Senate to carve out the ‘permitted’ purposes listed above. A mere four months after the CWC’s entry into force, a situation arose in the Former Yugoslavia that made parties to the newly established convention uneasy. As I wrote in the 1998 SIPRI Yearbook:

On 28 August 1997 heavily armed troops of the North Atlantic Treaty Organization (NATO)-led Stabilization Force (SFOR) had to evacuate more than 40 officers of the International Police Task Force from the Bosnian Serb town of Brcko after clashes erupted between peacekeeping forces and civilians. In what was described as one of NATO’s worst confrontations in Bosnia and Herzegovina since the 1995 Dayton Agreement, US helicopters dropped tear-gas and soldiers fired warning shots to disperse the crowd. Another US unit used tear-gas in a second incident on 1 September after being attacked by about 250 people armed with sticks and stones near Bijeljina, a village close to Brcko.

One consequence was that because of the CWC states participating in UN-authorised missions became reluctant to deploy and have even declined to export lachrymatory agent to partner countries in peacekeeping operations. Concern about violating the CWC also subsided because the United States has to the best of my knowledge never exercised this reservation. Through practice – no further incidents since the one in the Former Yugoslavia seem to have occurred – it has subscribed to the international consensus about RCAs in armed conflict.

Or so it seems. On 27 September 2006, Joseph Benkert, Principal Deputy Assistant Secretary of Defense for International Security Policy (Acting), testified in a little-noticed hearing on ‘U.S. Policy and Practice with Respect to the Use of Riot Control Agents by the U.S. Armed Forces’ held by the Subcommittee on Readiness and Management Support of the Senate Committee on Armed Services. In it, he emphasised that in accordance with the policy statement in the National Defense Authorization Act for FY2006, section 1232 (emphasis added)

It is the policy of the United States that riot control agents are not chemical weapons and that the President may authorize their use as legitimate, legal, and non-lethal alternatives to the use of force that, as provided in Executive Order 11850 (40 Fed. Reg. 16187) and consistent with the resolution of ratification of the Chemical Weapons Convention, may be employed by members of the Armed Forces in war in defensive military modes to save lives, including the illustrative purposes cited in Executive Order 11850.

Benkert went on to describe how US troops train in the deployment of RCAs on the battlefield. (I am not aware of a more recent document clarifying the US position.)


Through the General Purpose Criterion the CWC bans all use of toxic chemicals by default. The convention, however, also identifies certain purposes as non-prohibited. Provided certain conditions are met, using RCAs for law enforcement and domestic riot control is one of the stated non-prohibited purposes.

The CWC does not authorise or legitimise CW use under specific circumstances. It says that if a toxic chemical is used and only used for one of the non-prohibited purposes, then that toxic chemical is not considered a CW. In other words, an RCA deployed for domestic riot control purposes is not a CW and such use falls outside the scope of the CWC.

The US position as clarified in Benkert’s statement to the Senate subcommittee is that RCAs are not CW, full stop. Put differently, RCAs do not fall under the CWC even if used on the battlefield. (There may be some irony in the fact that the US ratification resolution refers to CWC Article II, para. 7 to define RCAs regarding the scope of Executive Order 11850.)

If commentators express puzzlement about the lawfulness of deploying RCAs against protesters while the same toxic chemicals cannot be used in armed conflict, the US Department of Defense holds the opposite view: why is military use on the battlefield limited to specific circumstances (by the CWC ratification resolution and Executive Order 11850) when law enforcement can use them. In Benkert’s testimony (emphasis added):

It may be difficult for many Americans to understand why their Armed Forces can use riot control agents in only defined circumstances when they see their local law enforcement agencies using them effectively every day. The United States military must operate within the parameters of the Chemical Weapons Convention and Executive Order 11850, which constrain the ability of our Armed Forces to use riot control agents in offensive operations in wartime and do not apply to our colleagues in law enforcement.

The United States occupies a solitary position with its view that RCAs are not CW. It emerged in the late 1920s when former members of the Chemical Warfare Service promoted the use of RCAs for domestic law enforcement as a way of defeating ratification of the 1925 Geneva Protocol and thus preserving the option of chemical warfare. ‘Chemical weapon’ applied exclusively to lethal agents. This legal fight returned in the early 1970s when the US government announced its intention to resubmit the Geneva Protocol for Senate assent. Those in favour of excluding RCAs argued, just like in the 1920s, that the British and French texts of the agreement contain different language, namely the more restrictive ‘asphyxiating, poisonous or other gases’ versus the supposedly more permissive ‘gaz asphyxiantes, toxiques ou similaires’. Pointing out that both texts are equally authentic, they argued that ‘similar’ refers to ‘asphyxiating’ and ‘toxic’ and does not mean ‘analogous’ or ‘other’. Already in 1930 France and Great Britain declared in the League of Nations they considered RCAs to fall under the Geneva Protocol and that no difference in meaning exists between the English and French texts. Other countries formally endorsed that position.

The US position on RCAs in armed conflict is tenuous. CWC Article XXII states that the main text of the CWC cannot be subject to reservations. Moreover, according to Article 8, 2 (b) (xviii) of the Rome Statute such use would constitute a war crime, more so as the provision uses the language (both English and French) of the 1925 Geneva Protocol. While the United States denies the jurisdiction of the International Criminal Court, world opinion would not look favourably on war crimes. In the Organisation for the Prohibition of Chemical Weapons it might also find itself in a rather isolated position.

In conclusion

Contrary to widespread opinion, the US government views RCAs as lawful weapons of war under conditions it has defined for itself in Executive Order 11850 and in line with the Senate resolution ratifying the CWC. It has the military doctrine and implements a training programme to deploy such weapons. The United States appears to have refrained from military interventions supported by RCAs. However, with the rise of counter-terrorism operations the line separating law enforcement from armed conflict has blurred. Today, the safeguard that only the US President may authorise military RCA use cannot be considered secure any more. The tendency since the 2001 terrorist attacks against New York and Washington to securitise international relations and militarise domestic law enforcement may equally erode formal and informal restraints.

Establishing legal constraints on police use of RCAs based on a general humanitarian or human rights idea that RCAs are banned in armed conflict but not against one’s own citizens may not hold true for the United States. As the US government seems to believe that military use is (unfairly?) constrained relative to law enforcement, one may expect divisive political debates absent an unequivocal ban on all uses of RCAs.

Such an unequivocal ban would also have to include the sale and use of so-called self-defence chemical sprays such as Mace and OC (oleoresin capsicum) aerosols.

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